Hi there CobraJet,
Several years ago, i got my complete system custom made up by a local car audio specialist for my '73 Vert. Regards the sub setup, i went the sub with amplifier choice. The speaker box enclosure and mounting platform enclosure were custom made up to spec and black carpeted to finish off. In the verts, that is the ideal place to mount your sub, as it doesn't interfere with the top going up and down, plus it gives you more usable space in your trunk area.
My speaker is mounted on the left and the amp in the middle, leaving a blank space on the right to mount another sub speaker if i choose to in the future.
I also ended up later on, fully timber lining and carpeting my entire trunk area(all walls, floor etc). This also helped and added to getting a more enhanced bass sound as the bass was allowed to permiate or move around through the entire trunk area. My sub is controlled through a built in sub woofer control incorporated in my Alpine head.
The thing with me is that i didn't go the subwoofer way to chase that insane, over the top duuf, duuf thumping bass that has become very popular with the younger generations and their fav music. You know when you pull up at the stop lights, and your windows are all wound up, and the guy next to you has his car audio going full tilt with the sub, and the thumping bass line is all you hear.
When i'm driving around these days with the top down, i find myself tending to turn down the volume a lot when i am stopped in traffic and other drivers are around me. I do this a matter of courtesy to others so as not bug them with putting up with a blaring stereo. It is naive to believe that everyone out there loves your musical choices or taste just as much as you do, and should be forced to enjoy it along with you.
I just wanted a more pronounced bass presence to enhance the overall sound of my music, and i certainly achieved that. Going with the sub was a wise investment, as it really bought the whole car audio setup to a new level of enjoyment. Fantastic bass response was achieved and it completed the treble, mid range and bass bottom end balance. With convertibles, a lot of bass is lost when driving around with the top down and you are experiencing a fair lot of road noise competing with your tunes. I wouldn't be without my sub to complete the sound. See my pics below.